Question about brands

We are in the middle of renovating our bathroom and are at the point of picking a mixing valve and a sink faucet. We are purchasing from a local bath showroom/plumbing supply so everything we are buying hopefully will be a better quality than from the big box stores.

The shower is only 36" x 36" and is going to be a hand held; at this point I believe it's going to be a Grohe Relaxa Ultra 5 spray pattern. Basically there's about $100 difference between that and American Standard or Delta - not too big of a deal.

But now I need to get into the shower's mixing valve and faucet and the place where I am buying the supplies sells American Standard, Grohe and can get Delta. I've heard not so good things about American Standard but I am not in the business.

The saleslady told us that the American Standard plumbing fixtures are great and she wasn't that big on Delta. We haven't really seen a faucet that we like in Grohe so that is probably not going to be one of our choices.

So my questions to you are - does it really matter? And does American Standard make sub par products?